The sister of a man gunned down on his doorstep overnight has claimed he was not involved in gangland crime.

"Gentle Giant" Tom Farnan (37) was blasted to death after he answered his front door on Kilcronan Close, Clondalkin in West Dublin.

The dad-of-one had a number of convictions for minor offences but his heartbroken family have insisted he was not involved in organised crime or gangland feuding.

Younger sister Jenny Farnan told Independent.ie: "Waking up and still living the nightmare how can this life be so cruel.

"Words can't describe how much I'm going to miss him. My heart is broken I still can't believe it."

She said the family could not understand why he was killed and insisted that she didn't want to speculate: "I just want it put out there that he was not involved in any of the gangland or criminal activities.

Gardai at the scene of the fatal shooting at Kilcronan Close in Clondalkin

"He was just a normal decent man, a big brother, a loving son and a brilliant father."

She continued: "He was the best brother I could have ever asked for. If anybody asked for anything then he would do it for them."

Gardaí believe the lone gunman knocked on Mr Farnan's door on Kilcronan Close before opening fire.

This afternoon gardaí issued a fresh appeal for help catching his killers.

A spokesman said: "From initial investigations it appears that a lone male entered the hallway of the house at the above location and fired a number of shots fatally injuring a 37-year-old man. The man was pronounced dead at the scene.

"The lone male then left the scene and is believed to have run along Kilcronan Close onto Grand Canal and then exited onto the green area towards Lock View Road."

The hitman was described as wearing all black clothing, black runners, black tracksuit and may have been wearing a balaclava. He is also described as being short in height.

A full investigation has commenced and an incident room has been established at Clondalkin Garda Station.

Investigating Gardaí are appealing for witnesses, particularly those people who were in the area prior to the incident and immediately after the shooting and who may have information or who may have seen anything unusual or suspicious to contact them at Clondalkin Garda Station on 01 666 7600 The Garda Confidential Line, 1800 666111 or any Garda Station.